1. Field of the Invention
The present invention relates to an image encoding apparatus, an image encoding method, and a computer program, and more particularly, to a technique capable of executing an intra-prediction operation at a high speed with a simple configuration in image encoding.
2. Description of the Related Art
In the past, a technique capable of transmitting and accumulating image signals effectively by using the redundancy of the image signal efficiently was developed, when a video for broadcast is transmitted and recorded, for example. This technique executes data compression of an image signal by motion compensation and orthogonal transform such as discrete cosine transform in conformity with the MPEG (Moving Picture Experts Group) or the like.
For example, the MPEG2 (ISO/IEC 13818-2) is a method that is defined as a general image encoding method. This method is defined so as to correspond to both an interlacing scanning method and a progressive scanning method and so as to correspond to both a standard resolution image and a high-definition image. The MPEG2 is widely used in various applications.
A standard encoding method ensuring a higher encoding efficiency than that of the MPEG2 has been developed as the Joint Model of Enhanced-Compression Video Coding method and standardized as the H.264/MPEG-4 AVC (ITU-T Rec.H.264 ISO/IEC 14496-10 AVC).
In this kind of encoding method, an in-image prediction operation (intra-prediction operation) and an inter-image prediction operation (inter-prediction operation) are executed. For example, Japanese Unexamined Patent Application Publication No. 2007-150913 discloses a method of storing at least ones of pixel signals of an original image vertically adjacent to the left side of an encoding target block (encoding target block) and pixel signals of the original image adjacent horizontally on the upper side of the intra-prediction target block. The method is disclosed such that the intra-prediction operation is executed with a smaller cycle number by using the stored pixel signals and pixel signals of a block (encoded block) of an image encoded by encoding and decoding.